Physics–Guided Neural Networks for Inversion–based Feedforward Control applied to Linear Motors

Abstract

Ever–increasing throughput specifications in semiconductor manufacturing require operating high–precision mechatronics, such as linear motors, at higher accelerations. In turn this creates higher nonlinear parasitic forces that cannot be handled by conventional feedforward controllers. Motivated by this problem, in this paper we develop a general framework for inversion–based feedforward controller design using physics–guided neural networks (PGNNs). In contrast to black–box neural networks, the developed PGNNs embed prior physical knowledge in the input and hidden layers, which results in improved training convergence and learning of underlying physical laws. The PGNN inversion–based feedforward control framework is validated in simulation on an industrial linear motor, for which it achieves a mean absolute tracking error twenty times smaller than mass–acceleration feedforward.